As sermons go, it was not the kind of pulpit performance that -- when it was given -- created a buzz in the pews. The young Catholic priest's voice was flat and subdued, his face calm but not expressive.

After all, he was only a year or so into his priesthood and preaching was still rather new to him. On this day he was working with a sobering text from the Gospel of Luke in which Jesus looks over the city of Jerusalem and weeps, knowing that death and destruction looms in the future.

So that was what Father Kenneth Walker preached about, in a sermon captured on video that has gone viral on the Internet in the days after he was gunned down, at 28 years of age, by a burglar at Mother of Mercy Mission parish near downtown Phoenix. He talked about forgiveness and the need for people living in a sinful, broken and violent world to realize that they may not have much time remaining to get right with God.

"God is all merciful, but he is also perfectly just," he said. "He will not prevent something from happening, if we bring it about by our own choosing. Nevertheless, God gives time and opportunity to repent before he lets the consequences fall upon us."

The Bible and church history are full of cases in which God warns people to flee wickedness, he said. In some cases, saints and martyrs suffered and died while God gave a wayward land more time to repent.

"We are in a similar situation today, since we are now living in a world that is increasingly rejecting Christ and casting him out of the public forum," said Walker. "We have grown far too attached to our own knowledge, our technology and our worldly pleasures -- such that we have forgotten God and what he has done for us."

Look around, he said. These are troubling times for Catholics who strive to practice the ancient traditions of their faith.

Walker died of multiple gunshot wounds on June 11, after what police reports describe as a late-night burglary at the parish rectory that went wrong. Another priest, 56-year-old Father Joseph Terra, was brutally beaten in the head with an angle iron.

Early this week, police arrested a homeless man with a lengthy criminal record and charged him with murder and assault.

Even before that arrest, Bishop Thomas Olmsted of Phoenix told television crews after a Mass that these urban priests -- who spent so much time of their time serving the poor -- would not want the church to turn from its mission. "We cannot run away at times like this," he stressed.

Both of the priests were ordained into the Priestly Fraternity of St. Peter, an order created by Pope John Paul II at the encouragement of the cardinal who would become Pope Benedict XVI. Its parishes exist to maintain Catholic traditions celebrated in the 16th century Tridentine Latin Mass. In a poignant detail, Terra confirmed that, even though he was critically injured, he was able to administer the last rites to Walker, almost certainly in Latin.

In his sermon months earlier, Walker quietly defended many of Catholicism's most controversial teachings, at one point listing abortion, artificial contraception, pornography, sexual promiscuity and "attacks on the family" as blasphemies against God.

But Christians are not called to dwell on issues of sin and destruction, he said, but to focus on the heart of Christianity, which is love, repentance and forgiveness.

"If real danger is present, it is necessary to be aware of it and to take measures to avoid it. It is a mother's love that tells her 5-year-old son not to play in a busy street. ... The devil only has power over us insofar as we let him or if we rely on ourselves -- like a little boy who thinks he knows better."

Out in the pews a cellphone began ringing loudly, over and over, as the young priest quietly finished his sermon.

For believers, he said, the goal is not to seek "perfect happiness in this world, with its fleeting joys and empty promises, like a single firecracker that gives one burst of fire and excitement and then is gone. Let us spend our lives in preparation for the eternal life of heaven, where there is no more death or destruction."